A former MI5 agent has said that former Beatle John Lennon helped fund the IRA in the early 1970s.

David Shayler told The Observer that he read the allegation in an MI5 file.

He also told the paper that an MI5 source within the Workers' Revolutionary Party (WRP) - whose most famous member was actress Vanessa Redgrave - claimed Lennon donated tens of thousands of pounds to their cause too.

The claims come hours after a US judge granted a Californian professor permission to see three letters relating to the FBI files on Lennon, who was shot dead by a deranged fan in 1980.

Professor John Wiener has been campaigning for 17 years to gain access to Lennon's FBI files.

Interest in Lennon remains high 20 years after his death

He told BBC News Online he was sceptical about claims that Lennon had donated money to the IRA and the WRP.

Prof Wiener, speaking from his Los Angeles home, said: "It seems on the face of it wrong.

'Supported civil rights movement'

"After all, he was closely associated with the Red Mole newspaper which was run by Tariq Ali and Robin Blackburn. This was a direct alternative to the WRP."

Prof Wiener said there was no doubt Lennon sympathised with the civil rights movement in Northern Ireland.

"John wrote a song called The Luck of the Irish which was a tribute to the victims of Bloody Sunday.

"He joined Troops Out marches in New York and it was well known that he identified with, and spoke out in favour of, the Irish civil rights movement. But that doesn't mean that he provided financial support for the IRA," he said.

David Shayler says he saw the report in an MI5 file

Prof Wiener, who has written a book about Lennon and the FBI entitled Gimme Some Truth, said it was possible MI5 had been misinformed about Lennon and the IRA.

"They were certainly misinformed about his support for the WRP and that makes me worried whether they were wrong with the IRA," he said.

Official Secrets Act broken

The claims about Lennon are the latest revelations from Mr Shayler.

He has made a string of intelligence disclosures since 1997 and is in exile in Paris after fleeing the UK under threat of arrest for breaking the Official Secrets Act.

Beatles biographer Hunter Davies told The Observer: "I wouldn't be at all surprised if he (Lennon) gave money to the IRA. John liked stirring it up."

Meanwhile the US federal authorities have been given 28 days to appeal against Judge Brian Robbins' decision to release the letters to Prof Wiener.

Prof Wiener's book was published last year

The letters are correspondence between the US Government and an unnamed foreign government - believed to be the British - dating from 1998.

Prof Wiener said: "The US Government asked the foreign government if it wanted the FBI files to remain classified. The reply was that it did and it reiterated this in January 1999."

'Culture of secrecy'

He said: "This is a blatant case where we know the content of the information being withheld and we know it is inaccurate.

"It is a vivid example of the excesses of this culture of secrecy which seems to pervade on both sides of the Atlantic."

The US Government, and its unnamed correspondent, claimed national security was at stake.

But Prof Wiener told BBC News Online: "This is not 'national security' information. It consists of 30-year-old reports on the political activities of a dead rock star."